CP-49876: Create spans for observer.py itself

Creates two spans for observer.py, one for the entire script and one for
the opentelemtry import statements. This fixes the current discrepancy
between the sm script span and the outer xapi span.

Signed-off-by: Steven Woods <[email protected]>

python3/packages/observer.py

@@ -20,6 +20,17 @@
 passed script without any instrumentation.
 """
 
+import time
+
+def to_otel_timestamp(ts):
+    return int(ts * 1000000000)
+
+observer_ts_start = to_otel_timestamp(time.time())
+observer_mono_start = time.monotonic()
+
+def current_otel_time():
+    return observer_ts_start + to_otel_timestamp(time.monotonic() - observer_mono_start)
+
 import configparser
 import functools
 import inspect
@@ -117,6 +128,9 @@ def _init_tracing(configs: List[str], config_dir: str):
 
         # On 3.10-3.12, the import of wrapt might trigger warnings, filter them:
         simplefilter(action="ignore", category=DeprecationWarning)
+
+        import_ts_start = current_otel_time()
+
         import wrapt # type: ignore[import-untyped]
         from opentelemetry import context, trace
         from opentelemetry.baggage.propagation import W3CBaggagePropagator
@@ -127,6 +141,8 @@ def _init_tracing(configs: List[str], config_dir: str):
         from opentelemetry.trace.propagation.tracecontext import (
             TraceContextTextMapPropagator,
         )
+
+        import_ts_end = current_otel_time()
     except ImportError as err:
         syslog.error("missing opentelemetry dependencies: %s", err)
         return _span_noop, _patch_module_noop
@@ -359,6 +375,12 @@ def _patch_module(module_name):
     for m in module_names:
         _patch_module(m)
 
+    # Create spans to track observer.py's setup duration
+    t = tracers[0]
+    with t.start_as_current_span("observer.py:init_tracing", start_time=observer_ts_start):
+        import_span = t.start_span("observer.py:imports", start_time=import_ts_start)
+        import_span.end(end_time=import_ts_end)
+
     return span_of_tracers, _patch_module